This invention relates to a process for the protection of a fat against oxidation, in which the fat to be protected is directly contacted with a vegetable material containing phenolic antioxidants.
In the food industry, antioxidants are used to retard the oxidative degradation of fats by inhibiting the formation of free radicals. The food-quality antioxidants normally used may be of synthetic origin, for example butyl hydroxyanisole (BHA) and butyl hydroxytoluene (BHT) (although the use of these antioxidants is being increasingly opposed in food legislation), but are preferably of natural origin, mainly vegetable origin emanating from plant extracts. Rosemary is at present the most widely used starting material in this field.
Various methods have been used to extract the antioxidant principles of vegetable materials and to convert into powder form or into more or less viscous liquids. Among the methods which lead to an antioxidant in powder form, a two-stage extraction involving the successive use of hexane and ethanol is proposed, for example, in European Patent Application Publication No. 0 307 626.
As an example of a process leading to a liquid antioxidant, European Patent Application Publication No. 0 507 064 describes a process for solubilizing antioxidants of vegetable origin in a medium-chain triglyceride (MCT) with the aid of solvents. Medium-chain triglycerides are liquid over a very broad temperature range, are capable of withstanding oxidative degradation and have a high dissolving potential for antioxidants of vegetable origin.
The problems addressed by the present invention were directly to dissolve antioxidants of vegetable origin in a fat to be protected by simple mechanical extraction, avoiding the use of solvents which would have to be eliminated. Where the fat is an oil, the objective was to provide a clear, non-thixotropic liquid solution of antioxidants of vegetable origin in a lipidic support which would not form any deposits on storage.